<?
    class PrincipioLab_Validate_Request_String extends PrincipioLab_Validate_Request
    {
        public function isValid($value)
        {
            if (parent::isValid($value))
                return PrincipioLab_Validate_Condition::checkValid(Zend_Controller_Front::getInstance()->getRequest()->getParam($this->field) != "", $this->message);

            return false;
        }
    }
?>